1. Punctuation: since it is a compound element, no comma is needed.

2. The tiger slept on the large tree branch but kept a watchful eye open.
Weak sentence :
The tiger slept on the large tree branch, but it kept a watchful eye open.
(compound sentence requires a comma)
  Model sentence (PCL):
The tiger slept on the large tree branch but kept a watchful eye open.
(compound element sentence does not require a comma)
1. The two boys picked blueberries, and they made a pie.

3. The two boys picked blueberries and made a pie.3
s v v
The two boys picked blueberries and made a pie.
(compound element sentence does not require a comma)

4. compound sentence—comma4
compound sentence—comma
S V S
3. The monkeys climbed the trees, and they V
searched for food. 

5. 3. The monkeys climbed the trees and searched for food.5
Punctuation: compound element—no comma
3. The monkeys climbed the trees and searched for food.

6. 5. The host greeted us at the door, and the host took our coats.
Punctuation: since these are compound sentences, commas are required.
4. When we left, Lisa closed the curtains, and she turned out the lights.
5. The host greeted us at the door, and the host took our coats. 
6. They were distant relatives, but they were very friendly relatives.

7. 4. When we left, Lisa closed the curtains and turned out the lights. 7
Punctuation: since these sentences have compound elements, no comma is required.
4. When we left, Lisa closed the curtains and turned out the lights.
5. The host greeted us at the door and took our coats. 
6. They were distant but very friendly relatives.

8. The tiger slept on the large tree branch but kept a watchful eye open.8
Directions: Select the two sentences that are punctuated correctly.
The tiger slept on the large tree branch but it kept a watchful eye open.
The tiger slept on the large tree branch but kept a watchful eye open.
The two boys picked blueberries, and they made a pie.
The two boys picked blueberries, and made a pie.

9. The two boys picked blueberries, and made a pie.9
Directions: Select the two sentences that are punctuated correctly.
The tiger slept on the large tree branch but it kept a watchful eye open.
The tiger slept on the large tree branch but kept a watchful eye open. COMPOUND ELEMENT CORRECT—NO COMMA
The two boys picked blueberries, and they made a pie. COMPOUND SENTENCE CORRECT NEEDS COMMA
The two boys picked blueberries, and made a pie.

10. Appositives—Compound Element 9
Appositives—Compound Element
Once a bright student, Kostya has received poor marks and is now unable to go to college.